Human and non-human primates rely on their abilities to manipulate objects with their hands. In order for complex abilities such as bilateral coordination of the hands, and manual dexterity to exist, a complex neural circuit that precisely integrates the somatosensory system with the motor system must be present in the primate brain. Cortical area 3a has been implicated as a relevant station in this integrative network. The present proposal represents a thorough investigation of the topographic organization and anatomical connections of area 3a in two primate species, macaque monkeys and marmoset monkeys. Multi-unit electrophysiological recording techniques will be used to determine the topographic organization of area 3a. A combination of fluorescent tracers and wheatgerm agglutinin conjugated to horseradish peroxidase (WGA-HRP) will be used to determine the anterograde and retrograde cortico-cortical, and cortico-thalamic connections of area 3a. The results of these experiments will provide critical information on a cortical area that may be involved in the integration of somatic inputs and motor outputs. By attaining a better understanding of how these two systems work together, these results can further contribute to our understanding of the recovery of sensation and function that occurs after a peripheral denervation, such as the loss of a hand or arm.